Structure, method and system for measuring RIE lag depth

Abstract

Structures for measuring RIE lag depth of a semiconductor device, including: a first metal layer; a dielectric cap layer on top of the first metal layer; an electrical ground element formed beneath one or more portions of the dielectric cap layer and within the first metal layer, the electrical ground element being electrically grounded; and a second metal layer on top of the dielectric cap layer, the second metal layer having an array of one or more sub-arrays of metal wires, each sub-array being connected to a respective bond pad and having metal wires of a given width; wherein a distance from a bottom surface of the array of metal wires to a top surface of the dielectric cap layer is indicative of RIE lag depth. The disclosure also relates to methods and systems for measuring RIE lag depth and identifying the existence of an electrical short of a semiconductor device.

Description

TECHNICAL FIELD[0001]The subject matter disclosed herein relates to reactive ion etching (RIE) lag depth for semiconductor devices. More specifically, various aspects described herein relate to structures, methods and systems for measuring RIE lag depth and identifying the existence of electrical shorts of semiconductor devices.BACKGROUND[0002]The fabrication of deep trenches in semiconductor dielectrics is one method of making metallic wires, referred to as interconnects. A deep trench of somewhat trapezoidal shape is etched out of a dielectric layer by a commonly used dry etch method known as reactive ion etching (RIE). There is today an ever increasing need to make the deep trenches more narrow to conserve space on the substrate and, hence, to increase productivity. This reduction process is commonly referred to as scaling. The direct result of scaling is that the width of the deep trench ends up substantially reduced. In order to maximize the cross-sectional area of the intercon...

AI Technical Summary

Benefits of technology

Enables accurate identification of RIE lag depth and electrical shorts without destructive testing, using less expensive electrical measurements, thus improving semiconductor device reliability and reducing analysis costs.

Problems solved by technology

With the requirement of scaling, the control of deep trench side wall passivation has become a fundamental issue and an impediment in achieving deeper trenches.

However, the presence of a thick passivation film on the entire inner surface of the deep trench during the etch process leads to a significantly slower etch rate.

Due to misprocessing, poor process setup, etc., RIE lag can cause wide width metal to short to underlying metal even though smaller width metal have depths that are on target and are not shorted.

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